Thread-chain holding devices for sewing machines



May 23, 1967 A. P. STEINER 2 THREAD-CHAIN HOLDING DEVICES FOR SEWING MACHINES Filed Jan. 6, 1965 2 SheetsSheet 1.

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INVENTOR. Adam P. Steiner WITNESS BY AM MQ 4 7W4 f AT OR'NEY A. P. STEINER May 23, 1967 THREAD-CHAIN HOLDING DEVICES FOR SEWING MACHINES Filed Jan. 6, 1965 2 Sheets-Sheet 2 a 4 Fig.9

INVENTOR. Adam P. Steiner WI TNESS ,zwwy,

M 7. law-J ATTORNEY United States Patent Office 3,320,915 Patented May 23, 1967 3,320,915 THREAD-CHAIN HOLDING DEVICES FOR SEWING MACHINES Adam I. Steiner, Union, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Jan. 6, 1965, Ser. No. 423,781 16 Claims. (Cl. 112--253) This invention relates to thread-chain holding devices for sewing machines and more particuluarly to presserfoot mounted plungers for holding thread chains on chain stitch and lock stitch machines.

In chain stitch and lock stitch machines, after an article has been sewn, a thread chain is formed and fed by the feeding mechanism just as the sewn article was fed until the thread chain is cut, a succeeding article is sewn, or the machine is stopped. In the chaining off of the thread chain, it is necessary to hold the thread chain against the retrograde tendency of the stitch-forming mechanism to pull the thread chain back into the needle aperture as succeeding stitches are set. Presser feet having a special plunger-type chaining foot have been successfully used on lock stitch machines to hold thread chains against the aforementioned retrograde action. However, on chain stitch machines where the retrograde tendency is greater, prior chaining feet have not been very successful in holding thread chains because the relatively large areas of the sole plates reduce the holding pressures of the chaining feet. Increasing the spring pressures of the chaining feet has not helped, but in fact has been detrimenta l because the additional pressures have caused the teeth of the feed dogs to lacerate the thread chains. The thread-chain holding problem on chain stitch machines is particularly acute in dart sewing wherein the line of stitching is turned off at an angle near the end of the seam.

It is, therefore, a primary object of this invention to provide improved devices for holding thread chains on chain stitch and lock stitch machines.

Another object of the invention, is to provide improved devices for holding thread chains on chain stitch and lock stitch machines in dart sewing.

The main feature of the invention resides in the provision for a step of reduced thread-chain contact area on the sole plate of a plunger-type chaining foot in order to provide sufficient thread-chaining holding characteristics for chain stitch machines. In a modification of the invention, the step is adapted to cooperate with a beveled recess formed in the throat plate of the sewing machine.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a detail elevational view of the head-end of a sewing machine having a presser foot incorporating a chaining foot of the present invention;

FIG. 2 is an enlarged cross sectional view of the presser foot of FIG. 1 taken substantially along the vertical plane containing the axis of the needle;

FIG. 3 is a rear elevational view of the presser foot illustrated in FIG. 2;

FIG. 4 is a bottom plan view of the presser foot illustrated in FIG. 2;

FIG. 5 is a further enlarged cross sectional view of the chaining foot portion of the presser foot of FIG. 2;

FIG. 6 is a side elevational view of a presser foot incorporating a modification of the invention;

FIG. 7 is a cross sectional view of the presser foot of FIG. 5 taken substantially along the vertical plane containing the axis of the needle;

FIG. 8 is a rear elevational view of the presser foot illustrated in FIG. 7;

FIG. 9 is a bottom plan view of the presser foot illustrated in FIG. 7; and

FIG. 10 is a further enlarged cross sectional view of the chaining foot portion of the presser foot of FIG. 7.

With reference to FIGS. 1 to 5 of the drawings, a chaining foot embodying the invention is illustrated as incorporated in a sewing apparatus represented by a twothread chain stitch machine. It will be recognized that the invention can be incorporated in other types of chain stitch machines as well as in lock stitch machines.

The two-thread chain stitch machine is of a conventional type having a frame which includes a sewing head 10 and a bed 11. Formed on top of the bed is a work supporting surface 12 which includes a throat plate 13 provided with a needle aperture 14.

The stitch-forming mechanism includes a thread-carrying needle 15 and a thread-carrying looper 16. The needle is secured to an endwise reciprocating needle bar 17 which is mounted in the head of the sewing machine. The looper 16 is mounted on a looper bar 18 which is in turn mounted on a pivot shaft 19 in the bed of the sewing machine. Endwise loopseizing and shedding movements and lateral needle avoiding movements in timed relation with the needle reciprocation requisite to the concatenation of needle and looper threads into stitches are imparted to the looper by conventional mechanisms (not shown).

Secured to a feed bar 20 by means of a screw 21 is a feed dog 22. Feed advance motion is imparted to the feed dog through a feed-advance rock shaft 23' while feed lift motion is derived from a feed-lift rock shaft 24. The mechanisms for oscillating the rock shafts 23 and 24 may be conventional and are not shown. A fork-shaped pitman 25 formed at one end of the feed bar 20 embraces a roller 26 connected to a rock arm 27 to receive the feed lift motion from the feed-lift rock shaft 24.

A presser device or foot indicated generally at 28 is secured by means of a clamping screw 29 to a presser bar 30 which is mounted in the sewing head. A biasing means such as a spring baises the presser bar and with it the presser foot 28 toward the work supporting surface 12, 13 of the bed. Since the invention can be incorporated in many different types of presser feet, or indeed in a separate chaining foot, only that structure of the presser foot will be described which cooperates with the presser invention.

The presser foot 28 includes a shank 31 formed with a sole plate 32. Secured in spaced bearings 33 and 34 at the front of the presser foot shank is a shouldered pin 35. A second sole plate 36 is carried by the pin and housed in a recess 37 formed in the sole plate 32 of the presser foot. A biasing means represented by a coiled compression spring 38 is mounted on the narrow portion 39 of the pin 35 between a shoulder 40 of the pin and a face 41 of the bearing 33. The spring 38 biases the second sole plate 36 toward the work supporting surface 12, 13 of the bed. A stop means or collar 42 is adjustably secured to the pin 35 by means of a screw 43 to limit the downward movement of the sole plate 36.

Formed on the bottom of the second sole plate 36 is a step 44. The step is adapted to cooperate with a land 45 formed on the throat plate 13 to hold a thread chain 46 sandwiched therebetween against the retrograde action of the stitch-forming mechanism as succeeding stitches are set.

The step 44 has a width transverse to the line of Work feed less than the corresponding width of the sole plate 32 of the presser foot which assists a work piece 48 in holder the step 44 up in the recess 37 in the sole plate 32 of the presser foot and the leading edge 47 of the step 44 is rounded off to prevent damage to either the Work piece 48 or the thread chain 46. The remaining work contacting surface of the step may have a length parallel to the line of work feed of from 0.03 to 0.06 of an inch to reduce the contact area with the thread chain 46 and consequently increase the thread-chain holding power. The foregoing arrangement permits the use of a light spring 38 which in combination with the step 44 having a width transverse to the line of work feed less than the corresponding width of the sole plate 32 of the presser foot facilitates the upward holding of the step 44 by the work 48 without damaging the work.

Construction of the work contacting surface of the step 44 in line with the pin 35 increases the stability of the thread-chain holding device as does the use of the spaced bearings 33 and 34-. Incorporation of a thread guiding means represented by a notch 49 formed in the leading edge of the sole plate 36 lends additional control over the chaining off process. As shown in FIG. 7 on the upward stroke, the needle pulls the needle-thread limb of the thread chain 46 up into the notch 49 to center the thread chain relative to the step 44.

FIGS. 6 to 10 illustrate a modification of the invention. The modification is illustrated as incorporated in a presser device or foot indicated generally at 50 and a throat plate 51 which is adapted for mounting on a work supporting surface of a sewing apparatus. Except for modifications in the chaining feet, the presser feet may be the same for both embodiments of the invention. Therefore, although the presser foot 50 is somewhat different from the presser foot 28, it is contemplated that they may be essentially interchangeable as far as this invention is concerned.

The presser foot 50 includes a shank 52 formed with a sole plate 53. At the front of the presser foot shank, a pin 54 is mounted in a vertical bore or bearing 55. A second sole plate 56 is carried by the pin 54 and housed in a recess 57 formed in the sole plate 53 of the presser foot. A biasing means represented by a coiled compression spring 58 is mounted on the pin 54 in a counterbore 59 formed in the presser foot shank. The spring 58 is compressed between the face 60 of the counterbore 59 and the second sole plate 56 to bias the second sole plate toward the throat plate 51. A stop means or collar 61 is adjustably connected to the pin 54 by means of a screw 62 to limit the downward movement of the second sole plate 56. As indicated previously, it is to be understood that the shouldered pin 35 and the spaced bearings 33 and 34 of the device of FIGS. 1 to may be used in lieu of the pin 54 and the bearing 55.

Formed on the bottom of the second sole plate 56 is astep 63. The step has a beveled leading edge 64 which is adapted to mate with the beveled leading edge 65 of a recess 66 formed in the throat plate 51 to hold a thread chain 67 against the retrograde action of the stitch-forming mechanism to set a stitch. The leading edges 64 and 65 of the step and the recess in the throat plate 51 may be beveled at 45 degree angles to a plane perpendicular to the line of work feed. As in the device of FIGS. 1 to 5, a thread guiding means represented by a notch 68 is formed in the leading edge of the sole plate 56 to provide additional control over the chaining off process.

In operation, in the device of FIGS. 1 to 5, after the work 48 to which the thread chain 46 is attached has passed from between the step 44 on the sole plate 36 and the work supporting surface of the bed, the step in cooperation with the land 45 on the throat plate 13 holds the thread chain 46 against the retrograde action of the succeeding stitch-setting processes to establish proper chaining off.

In the modification of FIGS. 6 to 10, the step 63 cooperates with the beveled recess 66 in the throat plate 51 to hold the thread chain 67 after a work piece 69 has passed from between the step and the beveled recess in the throat plate. The thread chain 67 is made to conform to the configuration of the beveled leading edge 64 of the step to provide very positive holding power.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Having thus described the nature of the invention, what I claim herein is:

it. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a Work supporting surface on the frame having a needle aperture, a pressure device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the presser device toward the work supporting surface of the frame; said thread-chain holding device comprising a second sole plate mounted on the frame of the sewing apparatus in opposition to the work supporting surface of the frame, second means for biasing said second sole plate toward the work supporting surface, and a step on said second sole plate downstream in the normal line of work feed from the needle aperture for holding a thread chain against the work supporting surface after work to which the thread chain is attached has passed from between said step and the work supporting surface.

2. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a work supporting surface on the frame having a needle aperture, a presser device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the presser device toward the work supporting surface of the frame; said thread-chain holding device comprising a pin mounted in at least one bearing in the presser device, a second sole plate carried by said pin in a recess in the first sole plate, second means for biasing said second sole plate toward the work supporting surface, stop means .for limiting the movement of said second sole plate toward the work supporting surface, and a step on said second sole plate of less width transverse to the line of work feed than the corresponding width of the first sole plate and downstream in the normal line of work feed from the needle aperture for holding a thread chain against the work supporting surface after work to which the thread chain is attached has passed from between said step and the work supporting surface.

3. The thread-chain holding device of claim 2 in which the work contacting surface of said step on said second sole plate has a length parallel to the line of work feed of from 0.03 to 0.06 of an inch.

4. The thread-chain holding device of claim 3 in which the work contacting surface of said step on said second sole plate is substantially in line with said pin to increase the stability of said thread-chain holding device.

5. The thread-chain holding device of claim 4 in which said second sole plate has thread guiding means upstream in the normal line of work feed from said step.

6. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a work supporting surface on the frame having a needle aperture, a presser device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the presser device toward the work supporting surface of the frame; said thread-chain holding device comprising a pin having a shoulder at an intermediate portion and mounted in spaced hearings in the presser device, a second sole plate carried by said pin in a recess in the first sole plate, a coiled compression spring mounted on said pin between the shoulder and one of said spaced bearings for biasing said second sole plate toward the work supporting surface of the frame, stop means for limiting the movement of said second sole plate toward the work supporting surface, and a step on said second sole plate of less width transverse to the line of work feed than the corresponding width of the first sole plate and downstream in the normal line of work feed from the needle aperture for holding a threadchain against the work supporting surface after work to which the thread-chain is attached has passed from between said step and the work supporting surface.

7. The thread-chain holding device of claim 6 in which the Work contacting surface of said step on said second sole plate has a length parallel to the line of work feed of from 0.03 to 0.06 of an inch.

8. The thread-chain holding device of claim 7 in which the work contacting surface of said step on said second sole plate is substantially in line with said pin to increase the stability of said three-chain holding device.

9. The thread-chain holding device of claim 8 in which said second sole plate has thread guiding means upstream in the normal line of work feed from said step.

10. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a work supporting surface on the frame having a needle aperture, a presser device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the presser device toward the work supporting surface of the frame; said thread-chain holding device comprising a second sole plate mounted on the frame of the sewing apparatus in opposition to the work supporting surface of the frame, second means for biasing said second sole plate toward the work supporting surface, a recess in the work supporting surface downstream in the normal line of work feed from the needle aperture, and a step on said second sole plate for holding a thread chain against an edge of said recess in the work supporting surface after work to which the thread chain is attached has passed from between said step and said recess in the work supporting surface.

11. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a work supporting surface on the frame having a needle aperture, a pressure device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the pressure device toward the work supporting surface of the frame; said thread-chain holding device comprising a pin mounted in at least one bearing in the presser device, a second sole plate carried by said pin in a recess in the first sole plate, second means for biasing said second sole plate toward the work supporting surface of the frame, stop means for limiting the movement of said second sole plate toward the work supporting surface, a recess in the work supporting surface downstream in the normal line of work feed from the needle aperture and having its leading edge beveled, and a step on said second sole plate for holding a chain against the beveled edge of said recess in the work supporting surface after work to which the thread chain is attached has passed from between said step and said recess in the work supporting surface.

12. The thread-chain holding device of claim 11 in which the leading edge of said recess in the work supporting surface and the leading edge of said step on said second sole plate are beveled at approximately 4-5 degree angles to a plane perpendicular to the line of work feed.

13. The thread-chain holding device of claim 12 in which said second sole plate has thread guiding means upstream in the normal line of work feed from said step.

14. A thread-chain holding device in combination with a sewing apparatus which includes a frame, a work supporting surface on the frame having a needle aperture, a pressure device having a first sole plate mounted on the frame in opposition to the work supporting surface, and first means for biasing the sole plate of the pressure device toward the work supporting surface of the frame; said thread-chain holding device comprising a pin having a shoulder at an intermediate portion and mounted in spaced bearings in the pressure device, a second sole plate carried by said pin in a recess in the first sole plate, a coiled compression spring mounted on said pin between the shoulder and one of said spaced bearings for biasing said second sole plate toward the work supporting surface of the frame, stop means for limiting the movement of said said second sole plate toward the work supporting surface, a recess in the work supporting surface downstream in the normal line of work feed from the needle aperture and having its leading edge beveled, and a step on said second sole plate for holding a thread chain against the beveled edge of said recess in the work supporting surface after work to which the thread chain is attached has passed from between said step and said recess in the work supporting surface.

15. The thread-chain holding device of claim 14 in which the leading edge of said recess in the work supporting surface and the leading edge of said step on said second sole plate are beveled at approximately 45 degree angles to a plane perpendicular to the line of work feed.

16. The thread-chain holding device of claim 15 in which said second sole plate has thread guiding means up stream in the normal line of work feed from said step.

References Cited by the Examiner UNITED STATES PATENTS 456,198 7/1891 Marks 112-151 1,314,820 9/1919 Lombardi et al. 112-151 2,747,533 5/1956 Enos 112-252 2,915,996 12/1959 Charest 112-151 X 2,934,031 4/1960 Graf 112-151 X 2,988,031 6/1961 Reid 112253 JORDAN FRANKLIN, Primary Examiner.

PATRICK D. LAWSON, Examiner.

J. R. BOLER, Assistant Examiner. 

1. A THREAD-CHAIN HOLDING DEVICE IN COMBINATION WITH A SEWING APPARATUS WHICH INCLUDES A FRAME, A WORK SUPPORTING SURFACE ON THE FRAME HAVING A NEEDLE APERTURE, A PRESSURE DEVICE HAVING A FIRST SOLE PLATE MOUNTED ON THE FRAME IN OPPOSITION TO THE WORK SUPPORTING SURFACE, AND FIRST MEANS FOR BIASING THE SOLE PLATE OF THE PRESSER DEVICE TOWARD THE WORK SUPPORTING SURFACE OF THE FRAME; SAID THREAD-CHAIN HOLDING DEVICE COMPRISING A SECOND SOLE PLATE MOUNTED ON THE FRAME OF THE SEWING APPARATUS IN OPPOSITION TO THE WORK SUPPORTING SURFACE OF THE FRAME, SECOND MEANS FOR BIASING SAID SECOND SOLE PLATE TOWARD THE WORK SUPPORTING SURFACE, AND A STEP ON SAID SECOND SOLE PLATE DOWNSTREAM IN THE NORMAL LINE OF WORK FEED FROM THE NEEDLE APERTURE FOR HOLDING A THREAD CHAIN AGAINST THE WORK SUPPORTING SURFACE AFTER WORK TO WHICH THE THREAD CHAIN IS ATTACHED HAS PASSED FROM BETWEEN SAID STEP AND THE WORK SUPPORTING SURFACE. 